Crystal phase modulation of Pd‐Se hollow nanospheres for selective propylene electrooxidation to propylene glycol

Electrocatalytic propylene oxidation to 1,2‐propylene glycol (PG) offers advantages over thermocatalytic routes through milder reaction conditions and concomitant green hydrogen production. Diverging from conventional palladium oxide paradigms, for the first time we demonstrate hollow nanosphere Pd 17 Se 15 and Pd 7 Se 4 exhibiting phase‐dependent reactivity for propylene electrooxidation to PG. Pd 17 Se 15 presents superior selectivity and Faradaic efficiency for PG compared to Pd 7 Se 4 and achieves twice the PG Faradaic efficiency of commercial Pd/C, owing to its distinctive crystal phase and local coordination environments. In situ attenuated total reflection Fourier transform infrared spectroscopy with isotopic labeling reveals that enhanced performance originates from optimized propylene adsorption energetics and accelerated *OH generation via efficient water activation. Density functional theory calculations confirm that Pd 17 Se 15 facilitates propylene adsorption and exhibits lower energy barriers for sequential hydroxylation than Pd 7 Se 4 . This study establishes the Pd‐Se phase‐dependent correlation in propylene electrooxidation to PG and advances the sustainable electrochemical upgrading strategy of light olefins.